This invention relates to a source of ions for mass spectrometers. The mass spectrometer is important as a detector for trace substances which are present in levels of parts per thousand (ppth) or less because of its inherent sensitivity. An unknown material (sample) under investigation is ionized by the source prior to injection into the analyzer, or mass separator section, of the mass spectrometer.
For many applications requiring detection of such low levels of trace elements a direct sampling ion source is particularly attractive. Detection versatility of the instrument is enhanced considerably where all factors which may affect formation of ions from the sample by the source and the efficient extraction of the ions from the source are independently and individually controllable. Such factors include the mode of operation (positive or negative ions), reagent gas pressure and temperature and residence time of the reagent and sample ions.
Accordingly, it is an object of the present invention to provide a practical direct sampling ion source for mass spectrometry.
It is also an object of this invention to provide such an ion source wherein provision is made independently to vary and control all factors which affect the formation of ions from the sample to be analyzed and their efficient extraction from the source.